Amplification by the Phase-Locking Mechanism in a 4-Junction SQUID | NIST

Donald G. McDonald

M. Basler, W. Krech, K.Yu. Platov

Donald G. McDonald

It is shown that the phase-locking property of an array of Josephson junctions can be used as a basis for amplification. The particular device simulated is a superconducting quantum interference device (SQUID) with four junctions in the loop, rather than the usual one or two. Novel consequences of this design are that it allows direct rather than inductive coupling to the SQUID and, because of its potentially compact form, it probably can have a bandwidth well into the gigahertz range, in agreement with the simulations.

Marian Darula, P. Seidel, F. H. Busse +1 more

The dynamic properties of a superconducting quantum interference device (SQUID) containing arrays of Josephson junctions in a superconducting loop, and in particular the case of a four-junction SQUID, is analyzed theoretically via computer simulations. It is shown that phase locking of Josephson junctions determines the dynamic behavior of the SQUID. In the case of a stable phase-lock state hysteretic I-V curves as well as unusual voltage-flux dependencies appear. The influence of a small spread in the Josephson junction parameters upon the stability of the phase-lock state is investigated in parameter space.

S. A. Belonogov, Oleg V. Snigirev, S.S. Tinchev +1 more

I. Ya. Krasnopolin, Ralf Behr, J. Niemeyer

A direct comparison of two voltages at 0.6 V reproduced by programmable arrays with Nb/Al/AlOx/Al/AlOx/Al/Nb Josephson junctions was carried out using a SQUID as a null detector. The voltage difference was measured and found to be smaller than 1.2 × 10−17 V. Jumps of the current in the flux transformer loop can be attributed to phase-slipping events when the phase lock in the arrays is broken.